prop size

[messongo]

i have 1983 mako 23 inboard repower with crusader 350 5.7 will 4 blade prop help with speed ?

[cgmiller]

i have had a few Shamrock inboards and only spun 3 blade props. the only Shamrock guys spinning 4 blades props had diesels. you should be more concerned with proper efficiency than speed, you are limited in your rpm range with the 5.7. over 4000 rpms you will be sucking the fuel tank dry. I had repowered with a new 5.7 crusader and it cruised 3400 to 4200 rpms and wound up to 5000 rpms. I went from a 5.8 to a new 5.7 and had to cut 2.5 inches of pitch out of the prop to get it to wind up to the required wot. I ended up going slower burning more fuel. disappointing investment of 11 grand.